Borehole devices actuated by fluid pressure

Abstract

An apparatus for actuating a tool downhole in a borehole. The apparatus includes a body; a port to admit fluid pressure into the body; and apparatus within the body in fluid pressure communication with the port for actuating the tool in response to (1) a fluid pressure level communicated through the port in excess of a first fluid pressure level greater than the hydrostatic pressure level, followed by (2) a decrease in the fluid pressure level communicated through the port from the first fluid pressure level to a second fluid pressure level less than the first fluid pressure level.

What is claimed is 
     
       1. An apparatus for actuating a perforating device downhole in a borehole extending from the surface of the earth and containing fluid therein, said apparatus attached to an end of a tubing string extending from the surface of the earth and having said perforating device attached to the other end thereof, said apparatus comprising: a body;   a port for admitting fluid pressure into the body;   means within the body in fluid pressure communication with the port for actuating the device in response to (1) a fluid pressure level greater than a first predetermined fluid pressure level communicated through the port, the first predetermined fluid pressure level communicated through the port being in excess of the hydrostatic pressure level of said fluid in said borehole, followed by (2) a second fluid pressure level communicated through the port, the second fluid pressure level communicated through the port being less than the the first predetermined fluid pressure level; and   disarming means for rendering the actuating means inoperable through the application of fluid pressure through said tubing string to the disarming means thereby preventing the actuation of said perforating device while allowing retention of said perforating device on said tubing string to allow the removal of said perforating device with said tubing string when said tubing string is removed from said borehole, the disarming means including: a piston means slidably contained within said apparatus; and   a plug means engageable with the piston means to prevent fluid flow in said conduit string past the piston means to allow actuation of the disarming means by the application of fluid pressure through said tubing string     whereby the plug means is inserted into and moves through said tubing string when it is desired to disarm the means within the body for actuating the device by engaging the piston means permitting the disarming means to be subjected to the application of fluid pressure through said tubing string thereby preventing the actuation of said perforating device by said apparatus while allowing retention of said perforating device on said tubing string to allow the removal of said perforating device with said tubing string when said tubing string is removed from said borehole.   
     
     
       2. The apparatus of claim 1, wherein the body is adapted to be coupled to said tubing string in the borehole and the port is positioned on the body such that the port is in fluid pressure communication with the interior of said tubing string when the body is coupled thereto. 
     
     
       3. The apparatus of claim 2, wherein the body is adapted to be coupled to a perforating gun and the means for actuating the device is adapted to actuate the perforating gun. 
     
     
       4. The apparatus of claim 1, wherein the body is adapted to be coupled to a perforating gun and the means for actuating the device is adapted to actuate the perforating gun. 
     
     
       5. The apparatus of claim 1, wherein the means for actuating the device comprises: means for storing the fluid pressure level which is greater than the first or the second fluid pressure level in response to the application of the fluid pressure level through the port in excess of the first predetermined pressure level; and   means for actuating the device in response to the stored pressure level and the application of the second fluid pressure level through the port.   
     
     
       6. The apparatus of claim 5, wherein the storing means comprises: a fluid pressure chamber in the body;   a fluid pressure passageway communicating fluid pressure from the port to the fluid pressure chamber; and   means for closing the fluid pressure passageway in response to the communication through the port of a fluid pressure level in excess of the first predetermined fluid pressure level.   
     
     
       7. The apparatus of claim 1, wherein the body comprises a tubular member having a threaded coupling at a first end thereof adapted to make a threaded connection with a tubing string and the port is formed in the tubular member at the first end thereof to communicate fluid pressure between the interior of the tubular member and the interior of the tubing string; and wherein the actuating means comprises a fluid pressure chamber within the tubular body;   a fluid pressure passageway formed within the tubular body for communicating fluid pressure from the port to the fluid pressure chamber;   means for closing the fluid pressure passageway in response to the communication through the port of a fluid pressure in excess of the first predetermined fluid pressure level to store a fluid pressure level in the fluid pressure chamber; and   means for actuating the device in response to the stored fluid pressure level and the application of the second fluid pressure level through the port.   
     
     
       8. The apparatus of claim 7, wherein the means for closing the fluid pressure passageway comprises a second piston disposed in a first piston disposed, in turn, in a piston chamber sub connected to the tubular body and exposed at a first surface to fluid pressure in the fluid pressure passageway and exposed at a second, opposed surface to a second predetermined fluid pressure, the second piston means being operative to slide within the tubular body thus to block the fluid pressure passageway when the fluid pressure therein exceeds or equals the first predetermined fluid pressure level. 
     
     
       9. In a borehole containing fluid therein having a perforating gun suspended on an end of a tubing string adjacent an interval of the borehole to be perforated, the gun having a pressure actuated firing head comprising: a port for admitting fluid pressure into the firing head,   means within the firing head in fluid pressure communication with the port for actuating the perforating gun in response to (1) a first fluid pressure level greater than a first predetermined fluid pressure level communicated through the port, the first predetermined fluid pressure level communicated through the port being in excess of the hydrostatic pressure level of the fluid in the borehole, followed by (2) a second fluid pressure level communicated through the port, the second fluid pressure level communicated through the port being less than the first predetermined pressure level; and   disarming means for rendering the actuating means inoperative through the applicaton of fluid pressure through the tubing string to the disarming means thereby preventing the actuation while allowing retention of said perforating gun on said tubing string to allow the removal of said perforating gun with said tubing string when said tubing string is removed from said borehole, the disarming means including: a piston slidably contained within said pressure actuated firing head; and   a tubing string conveyed plug engageable with the piston to prevent fluid flow in the tubing string past the piston to allow actuation of the disarming means by the application of fluid pressure through the conduit string     whereby the tubing conveyed plug is inserted into and moves through said tubing string when it is desired to disarm the means within the firing head for actuating the perforating gun by engaging the piston permitting the disarming means to be subjected to the application of fluid pressure through said tubing string thereby preventing the actuation of said perforating gun by said pressure actuated firing head while allowing retention of said perforating gun on said tubing string to allow the removal of said perforating gun with said tubing string when said tubing string is removed from said borehole.   
     
     
       10. The apparatus of claim 9, wherein the port is in fluid pressure communication with the interior of the tubing string. 
     
     
       11. The apparatus of claim 9, wherein the port is in fluid pressure communication with the borehole annulus defined between the exterior of the string and the wall of the borehole. 
     
     
       12. The apparatus of claim 9, wherein the firing head is disposed below a packer means dividing the annulus between the tubing and the walls of the borehole into an upper annulus and a lower annulus. 
     
     
       13. The apparatus of claim 12, wherein the firing head is disposed beneath the perforating gun and the port is exposed to fluid pressure in the lower annulus.